Two of his _____ left for Europe.

Analyze the question The sentence is "Two of his _ left for Europe." We need the word form that fits after "Two of his."

Explain the concept "Two of his ..." is a partitive structure. It takes a plural noun because "two" refers to a number of people or things out of a larger group. For example: "Three of my cousins came," "Two of her books are missing."

A possessive form (friend's or friends') is only needed when something belongs to the friend. Here the friends are the ones doing the action (leaving), so no ownership is being shown. The word "his" already marks the possession.

Step-by-step solution

1. "Two" is a number above one, so the noun must be plural. This eliminates D (friend).
2. Nothing belongs to the friends. The sentence does not say "two of his friend's bags." This eliminates B (friend's) and C (friends').
3. "Friends" is plural and has no apostrophe. It fits: "Two of his friends left for Europe."

Answer The correct option is A. friends.

Tip Before you choose an apostrophe, ask: "Does something belong to this noun?" If the sentence has no object that is owned, use the plain plural. Also, with "two of his/her/their ...", always pick the plain plural noun.